In the three-dimensional (3D) stereo display technology, the 3D stereo display associated with a time sequence is considered as being quite mature. That is, images of the left eye and the right eye are alternately displayed on the basis of a time sequence so that the eyes of a viewer perceive the left-eye images and the right-eye images alternately. More particularly, the left eye of the viewer only perceives the left-eye images and the right eye of the viewer only perceives the right-eye images. For example, a pair of stereo glasses, having a left-eye shutter and a right-eye shutter, associated with a display capable of alternately displaying the left-eye images and the right-eye images, can provide 3D stereo images to the viewer.
FIG. 1 shows a schematic diagram of timing control of stereo images displayed by an LCD display and a pair of stereo glasses of the prior art. As shown, the LCD display alternately displays left-eye images and right-eye images. Since the LCD display is a hold-type display, each of pixels of the LCD display displays current pixel data continuously before being updated. Therefore, as shown in the diagram, during an interval in which a display image of the LCD display is updated with a left-eye image, the display image (e.g., a display image of a time point Ta illustrated at the bottom of FIG. 1) of the LCD display actually contains not only an updated left-eye image, but also a right-eye image that is not yet updated. Upon entering a vertical blanking interval, the display image of the LCD display is completely updated with the updated left-eye image (e.g., a display image of a time point Tb illustrated at the bottom of FIG. 1). Likewise, during an interval in which the display image of the LCD display is updated with a right-eye image, the display image (e.g., a display image of a time point Tc illustrated at the bottom of FIG. 1) of the LCD display actually contains not only an updated right-eye image, but also a left-eye image that is not yet updated. Upon entering a vertical blanking interval, the display image of the LCD display is completely updated with the updated right-eye image (e.g., a display image of a time point Td illustrated at the bottom of FIG. 1).
In order to avoid crosstalk, the pair of stereo glasses is only correspondingly switched to an open state during vertical blanking intervals. More specifically, the left-eye shutter of the pair of stereo glasses is opened during the vertical blanking intervals after the left-eye images have been updated, and when the current display image begins to be updated with the right-eye images, both of the left-eye and right-eye shutters of the stereo glasses are closed. Similarly, the left-eye shutter of the stereo glasses is opened during the vertical blanking intervals after the right-eye images have been updated, and when the current display image begins to be updated with the right-eye images, both of the left-eye and right-eye shutters of the stereo glasses are closed.
It is apparent from the foregoing description that, when viewing stereo images with a pair of stereo glasses, the images can only be perceived during vertical blanking intervals, which are rather short in a common image signal. Under such circumstances, since intervals that a viewer sees the images are extremely short, not only the viewer feels the images have inadequate brightness, but also an intended stereo effect may not be achieved as a result of left and right images of the stereo images appear as separate images for that the left and right images fail to form visual persistence in the viewer's brain. In order to provide a solution to above issue, the vertical blanking intervals need be extended to prolong intervals in which the stereo glasses are switched to an open state. In the prior art, to increase the vertical blanking interval, pixel data of an image signal is first written into a temporary memory, and is then read out from the memory according to a relatively faster read clock to generate an adjusted image signal. Through such approach, each data enable duration of a vertical data enable signal is reduced from reading the pixel data with the relatively faster reading clock, while a frame cycle of the adjusted image signal remains unchanged, so that the vertical blanking interval is extended as desired.
FIG. 2 shows a timing diagram of a vertical data enable signal of an image signal, before and after extending the vertical blanking interval with the prior art. A vertical data enable signal VDE1 in the unadjusted image signal includes a plurality of vertical data enable durations, each of which indicates a position of pixel data corresponding to an image frame in the unadjusted image signal. A vertical data enable signal VDE2 in the adjusted image signal similarly includes a plurality of vertical data enable durations, each of which indicates a position of pixel data corresponding to an image frame in the adjusted image signal. As shown in FIG. 2, a rising edge of a vertical data enable duration VDE2—n-1 of an (n−1)th frame of the vertical data enable signal VDE2 in the adjusted image signal is aligned with a rising edge of a vertical data enable duration VDE1—n of an nth frame of the vertical data enable signal VDE1 in the unadjusted image signal—it means the adjusted image signal falls one frame cycle behind the unadjusted image signal. Thus, the prior approach for increasing the vertical blanking intervals leads to delaying an adjusted image signal by at least one frame cycle compared to an unadjusted image signal, such that the delay in the adjusted image signal leads to in signal delay in certain applications. For example, in an application of television/computer game display, score performance of the user may be undesirably affected due to message hold-up from the delay of the adjusted image signal.